Cushion for sheet metal presses



March 1932- R. w. GLASNER ET AL 8,

CUSHION FOR SHEET METAL PRESSES Filed April 12, 1950 3 Sheets-Sheet l Edda najzaaw" March 8, 1932. R. w. GLASNER ET AL CUSHION FOR SHEET METAL PRESSES Filed April 12,1930 3 Sheets-Sheet 2 March 8, 1932. R. w-.' GLASNER ET AL CUSHION FOR SHEET METAL .PRESSES Filed April i2, 1950 source, a pressure regulating valve 33 being arranged in the pipe and a pressure gage 34 is also provided for the reservoir 30.

A gage glass 35 may also be provided for the cylinder 20.

A suitable packing 36 is provided to form a fluid tight joint between the plunger 26 and the bearing member 25.

The plunger 26 is hollow as at 37 and one,

end thereof is'shaped to form a valve seat 38 with which a-valve 39 co-operates. Connected with the valve is a stem 40,013 a diameter considerably less than the internal diameter of the plunger 26. The valve stem passes through suitable bearings 41 in the plunger and extends fora considerable distance beyondthe piston 27 and into the cylinder 28, a nut or collar 42 being provided on the end of the valve stem'and a spring 43 encompasses the valve stem with one end abutting the collar 42 and the other end resting upon the bearing 41. The normal tendency of the spring 43 is to close the valve 39 by holding a t e same upon its seat 38. c,

Arranged within the cylinder 28, preferably to extend thereacross and within the path of movement of the endof the valve stem 40, is an abutment 44 which, when the piston 27-and plunger 26 approach the; limit of their movement in one direction, will be contacted bythe end of the stem 40 and the valve 38 will, be opened against the stress of the spring 43. v e

- .The bearing member 25 is provided with a reduced interior portion adjacent one end thereof to form a shoulder 45, fora purpose to be set forth. I

Liquid is supplied .to the cylinder 22 and thecy'linder28ineany suitable manner (not shown) and fluid pressure such as air pressure is supplied to the resewoir 30 through the pipe 32. The normal position of the parts are as shownin Figure 1, that is with the pressure pad 20 abutting the lower face of the bed 160i the press and the piston 21 at the limit of its return movement in the cylinder 22,

and one end of the. plunger 26 willengage and rest upon the shoulder 45 in the hearing; member 25-while the'spring 43 will hold the valve 39v closed. The predetermined resistance pressure is maintained in the reser-. voir 30 and will act upon the liquid in the cylinder 28 to hold the piston 27 in its lowermost position, and the plunger 26 against the shoulder '45, when the ram of the press 13 is in an elevated position.

' when the ram descends and the die 15 cooperates, with the work holder 18 to operate upon the work 46, thepressure pad 20 will be lowered in the cylinder 22 to create a pressure upon the liquid column confined between the piston 21, the end of theplunger 26Land the valve 39.

As soon as the piston starts to move downwardly there will be an initial resistance of the liquid against the piston, which has a tendency to cause a shock to the mechanism.

In order to overcome this initial shock the plunger 26 and piston element 27 are provided. As soon as pressure is created upon the liquid in the column the pressure will be conveyed through the liquid column to the valve 39 and end of the plunger 26, causing the same to rise from the position shown in Figure 1 to the position shown in Figure 2 and the piston 27 and plunger 26 will continue to rise until the end of the valve stem 40 contacts with the abutment 44 (see Figure 3), after which a continued movement of the plunger 26 and piston 27 in the same. direction will cause the valve 39 to be opened and thereby permit liquid to escape from the liquid column into the cylinder 28 and reservoir 30. i

During the time that the plunger 26 and piston 27 are moving under such pressure the spring 43 will hold the valve 339 closed until the end of the stem 40 engages the abutment 44.

As soon as the ram 13 of the press starts to ascend the pressure in the liquid column will be relieved and the pressure in the reservoir 30 acting upon the liquid in the cylinder 28, will move the piston 27in the opposite direction and as soon as the end of the valve stem 40 moves out ofengagement with the abutment 44 the valve 39 will close and will remain closed until the end of the plunger 26 engages the pressure in thereservoir 30 upon the liquid in the cylinder 28 and in the plunger 26 will operateupon the valve 39 to open the same against the stress of the spring 43 and thereby permit liquid to flow back into the liquid column-to replace the liquid which had previously escaped therefrom.

With this improved construction there is provided a combined shock absorber, relief and check valve'as a unitary structure.-

The variation in pressure will be compensated by varying the pressure on the column of-liquid which in turn is effective on the piston 27 and the ratio of air pressure to the pressure obtained in the die cushion '22 is directly proportionate to the area of the pisston 27 and the'area of the plunger 26 which yields on a downward stroke of the press and serves as a shock absorber.

The relief valve is associated with the plunger of the shock absorber and is not rendered active until the limit of the stroke of the shock absorbing piston has been reached. The relief valve which operates at the upper end of the shock absorbing cylinder also serves as a check valve whichpermits the liquid to flow into the cylinder 22 to maintain the cylinder and the liquid column filled at all times.

While the preferred form of the invention shoulder 45., At this time,

several parts,

i What is claimedas new is:

1. Inasheetmetal press a pressure pad,

means for maintaining-a column of liquid forv yieldingly resisting the movementof said pad in one direction a shock absorber operated upon'by said'column ofliquid for overcoming the initial resistance of the'liquiduponsaid pressure pad, and Ya combined check and relief valve operatively connected with said shock absorber vand automatically actuated at a predetermined time in the cycle of operation of said shock absorber to permitthe escape of liquid fromsaid column to relieve the pressure therein, the said valve being automatically opened at a predetermined time in the cycle of the return movement of said pressure pad to back into said column. I r

2. In a sheet metal press a pressure pad,

permit liquid to flow means for maintaining a column of liquid for,

yieldingly resisting the movement of the pad inlone direction, a shockcabsorber operated upon by said column under pressure-0f said pad for overcoming the initial resistance of the liquid to the said movement ofsaid pad, a pressure accumulator reservoir for supplying resistance fluid to the shock absorber,a combined check and relief valve connected with the shock absorber, and means said valve being automatically opened at ancolumn and reservoir for overcoming the matically at a for positively opening said valve at a predetermined time in the cycle of operation of the shock absorber to permit liquid to escape from said column and into said reservoir,the

other time in the cycle of operation of the shock absorber by pressure in said reservoir to permit escaped liquid to flew back into said. columnof liquid.

'3. In a sheet metal press a pressure pad, I

-cylindencommunlcatlng wlth the IBSGIVOII,I

means for maintaining a column of liquid for yieldingly resisting themovementof the pad in one direction, ervoir, a shock absorber between the said shoclrof the initial resistance pressure of said column upon said pad, means operating autopredetermined time in the cycle of operation of the press for releasing some of the liquid from saidcolumn-into said reservoir, and means controlled by the-pressure in said "reservoir for subsequently supplying said column of liquid With the quantity of liquid previously released therefrom.

4. In a sheet metal ress a ressure ad means for maintaining a column of liquid for ieldin l resist-in the movement of said pad in one direction, a pressure accumulator container, means embodying a chack valve a pressure accumulatorres-H forcoverconiin'gfthe shock upon said padtby the initial resistance thereto bythecolumn' of liquid, positive means operating automat icallyat a, predetermined time in the cycle ofoperation of'the second recited means to permitcthe escape of some, of the liquid from said column and into said container to 'relieve the resistance pressure of said column, andmeans whereby the'pressure lIl'SZLld container illsubsequently open the said valve to permitliquid to bereturned to said column. 5. In a sheet metal press, a pressurelpad,

means'for maintaininga column of liquid for yieldingly resisting the movement of the pad in one direction, a pressure accumulator. reservoir, means embodying, a check andrelief valve intermediate said column andreservolr pressure in said reservoir; subsequently open-- into said column.

meansfor maintaininga column ofliquid for yieldingly resisting the inovementofsaid: I pad in one direction, a pressure accumulator, r

reservoir, a shock absorber intermediate-said ingsaidgvalve topermit liquid'to flow back 9 6. Inasheet metal press, alpressure pad,

for-controlling the pressure insaid column,"

column, and reservoir for overcominghther shock ofthe initial resistance, pressure of said column upon said 'pad,iacombinedfcheck V and relief valve connected with the shock absorber, means for automatically opening saidcolumn into said'reservoir, and means 7 whereby the said' valve' ,Will be subsequently perated to permit liqu'idto be deliveredinto; the said column. f

7. In asheet metal press apressurepad,

means for-maintaining a columnof-liquid for yieldingly: resisting the movementof said pad said, valve to permit liquid to escape'from a piston movablein the Cylinder, a plunger connectedwith the piston and movable in said column and uponivvhich plunger the liquidin the column acts. a fluid passage through said plunger 7 said colum'ncand shock, absorbenia'valve in said passage, means for openingsaidwvalve v to permit; escape of liquldfroin said column,

yieldingly resistingthe movement of said forming; communicationv between V pad inone directioma pressure accumulator V reservoirg a shock absorber intermediate said column and said reservoir, and embedyinga cylinder communicating with the reservoir, 1

through apiston'movable in the cylinder, a plunger connected with the piston and movable in said column andupon which plunger the liquid in the column acts, a fluid passage said plunger forming communication between said columnand shock absorber, avalve in said passage, means foropening said valve to permit escape of liquid from said column, and means whereby pressure yieldingly resisting pad in one direction,

, uid in the column acts, a fluid passage through escape of liquid from said column,

I said plunger forming communication between I said column and shock absorber, a valve in said passage, means arranged in the path of movement of aportion of said valve with said plunger for opening the valve to permit escape of liquid from said column, and means for subsequently opening said valve to permit return of liquidintosaid column.

10.*In a sheet metal press a pressure pad, means for maintaining a column'of liquid for yieldingly resisting the movement of said pad in one direction, a pressure accumulator reservoir, a shock absorber intermediate said column and said reservoir and embodying a cylinder communicating with the reservoir, a piston movable in the cylinder, a plunger connected with the piston and movable in said columnand upon which plunger the liquid in the column acts, a fluid passage through said plunger forming communication between. said column and shock absorber, a valve in said passage, means arranged in the path of movementof a portion of said valve with said plunger for opening the valve to permit means for arresting the return movement of the plunger, and means'whereby said valve will be automatically opened after said plunger has been arrested, to permit liquid to be delivered into said column;

11. In a sheet metal press a pressure pad, means for maintaining a column of liquid for yieldingly resisting the movement of said pad in onedirection, a pressure accumulator reservoir, a shock absorber intermediate said column and said reservoir and embodying a cylinder communicating with the reservoir, a piston movable in the cylinder, a plunger connected with the piston and movable in said column and upon which plunger the liquid in the column acts, a fluid passage through said plunger forming communication between said column and shock absorber, a valve insaid passage, means arranged in the path of movement of a portion of said valve with said plunger for opening the valve to permit escape of liquid from said column, means for arresting the return movement of the plunger, and means whereby the pressure in said reservoir will operate to open said valve when said plunger has been thus arrested, to permit liquid to be delivered into said column.

In testimony whereof we have signed our names to this specification, on this 4th day of April, A. D. 1930.

RUDOLPH W. GLASNER. FREDRICHJ. RODE." 

